The preparation and properties of antidepressant substituted 1-dimethylaminopropyl-1-phenylphthalans (or 1-(3-dimethylaminopropyl)-1-phenyl-1,3-dihydroisobenzofurans) have been described in U.S. Pat. No. 4,136,193. The most interesting of these compounds contain a cyano-group, and one of these, 1-(3-dimethylaminopropyl)-1-(4'-fluorophenyl)-1,3-dihydroisobenzofuran-5-c arbonitrile, has shown great promise as a valuable antidepressant drug with few side effects.
It has been found, however, that the methods described in U.S. Pat. No. 4,136,193 for the preparation of this compound possess some problems in the scale-up to commercial production, and this has necessitated further research in an attempt to discover a shorter route to this compound and to avoid the risk involved in the metalation step used previously.